Aircraft are the lifeblood of an airline or any business that relies on such aircraft for timely movement of people and material between cities. An aircraft on the ground, especially for service or other maintenance, cannot generate revenue. The goal is to keep aircraft in an airworthy condition so that they are available for use as needed.
When an event such as a fault code or a prognostic alert, that is, any non-conformance condition occurs a decision must be made as to when and where to perform the service required. Optimizing the various factors of route, repair locations, parts availability, etc. to arrive at an optimal solution is a challenging problem.